Implement SnapStart Runtime Hooks

Cargo.toml

@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 members = [
     "lambda-http",
     "lambda-integration-tests",

examples/basic-runtime-hooks/.gitignore

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+/target

examples/basic-runtime-hooks/Cargo.toml

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+[package]
+name = "basic-runtime-hooks"
+version = "0.1.0"
+edition = "2021"
+
+
+# Use cargo-edit(https://github.com/killercup/cargo-edit#installation)
+# to manage dependencies.
+# Running `cargo add DEPENDENCY_NAME` will
+# add the latest version of a dependency to the list,
+# and it will keep the alphabetic ordering for you.
+
+[dependencies]
+lambda_runtime = { path = "../../lambda-runtime" }
+serde = "1.0.136"
+tokio = { version = "1", features = ["macros"] }
+tracing = { version = "0.1", features = ["log"] }
+tracing-subscriber = { version = "0.3", default-features = false, features = ["fmt"] }
+uuid =   { version = "1.4.1", features = ["v4"]}

examples/basic-runtime-hooks/README.md

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+# AWS Lambda Function example
+
+## Build & Deploy
+
+1. Install [cargo-lambda](https://github.com/cargo-lambda/cargo-lambda#installation)
+2. Build the function with `cargo lambda build --release`
+3. Deploy the function to AWS Lambda with `cargo lambda deploy --iam-role YOUR_ROLE`
+
+## Build for ARM 64
+
+Build the function with `cargo lambda build --release --arm64`

examples/basic-runtime-hooks/src/main.rs

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+// This example demonstrates use of shared resources such as DB connections
+// or local caches that can be initialized at the start of the runtime and
+// reused by subsequent lambda handler calls.
+// Run it with the following input:
+// { "command": "do something" }
+
+use lambda_runtime::{crac::Resource, service_fn, Error, LambdaEvent, Runtime};
+use serde::{Deserialize, Serialize};
+use std::cell::RefCell;
+use uuid::Uuid;
+
+/// This is also a made-up example. Requests come into the runtime as unicode
+/// strings in json format, which can map to any structure that implements `serde::Deserialize`
+/// The runtime pays no attention to the contents of the request payload.
+#[derive(Deserialize)]
+struct Request {
+    command: String,
+}
+
+/// This is a made-up example of what a response structure may look like.
+/// There is no restriction on what it can be. The runtime requires responses
+/// to be serialized into json. The runtime pays no attention
+/// to the contents of the response payload.
+#[derive(Serialize)]
+struct Response {
+    req_id: String,
+    msg: String,
+    secret: String,
+}
+
+struct SharedClient {
+    name: &'static str,
+    secret: RefCell<String>,
+}
+
+impl SharedClient {
+    fn new(name: &'static str, secret: String) -> Self {
+        Self {
+            name,
+            secret: RefCell::new(secret),
+        }
+    }
+
+    fn response(&self, req_id: String, command: String) -> Response {
+        Response {
+            req_id,
+            msg: format!("Command {} executed by {}.", command, self.name),
+            secret: self.secret.borrow().clone(),
+        }
+    }
+}
+
+impl Resource for SharedClient {
+    fn before_checkpoint(&self) -> Result<(), Error> {
+        // clear the secret before checkpointing
+        *self.secret.borrow_mut() = String::new();
+        tracing::info!("in before_checkpoint: secret={:?}", self.secret.borrow());
+        Ok(())
+    }
+    fn after_restore(&self) -> Result<(), Error> {
+        // regenerate the secret after restoring
+        let secret = Uuid::new_v4().to_string();
+        *self.secret.borrow_mut() = secret;
+        tracing::info!("in after_restore: secret={:?}", self.secret.borrow());
+        Ok(())
+    }
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    // required to enable CloudWatch error logging by the runtime
+    tracing_subscriber::fmt()
+        .with_max_level(tracing::Level::INFO)
+        // disable printing the name of the module in every log line.
+        .with_target(false)
+        // disabling time is handy because CloudWatch will add the ingestion time.
+        .without_time()
+        .init();
+
+    let secret = Uuid::new_v4().to_string();
+    let client = SharedClient::new("Shared Client 1 (perhaps a database)", secret);
+    let client_ref = &client;
+    tracing::info!("In main function: secret={:?}", client_ref.secret.borrow());
+
+    Runtime::new()
+        .register(client_ref)
+        .run(service_fn(move |event: LambdaEvent<Request>| async move {
+            tracing::info!("In handler function: secret={:?}", client_ref.secret.borrow());
+            let command = event.payload.command;
+            Ok::<Response, Error>(client_ref.response(event.context.request_id, command))
+        }))
+        .await?;
+    Ok(())
+}

examples/http-runtime-hooks/.gitignore

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+/target

examples/http-runtime-hooks/Cargo.toml

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+[package]
+name = "http-runtime-hooks"
+version = "0.1.0"
+edition = "2021"
+
+# Starting in Rust 1.62 you can use `cargo add` to add dependencies 
+# to your project.
+#
+# If you're using an older Rust version,
+# download cargo-edit(https://github.com/killercup/cargo-edit#installation) 
+# to install the `add` subcommand.
+#
+# Running `cargo add DEPENDENCY_NAME` will
+# add the latest version of a dependency to the list,
+# and it will keep the alphabetic ordering for you.
+
+[dependencies]
+lambda_http = { path = "../../lambda-http" }
+tokio = { version = "1", features = ["macros"] }
+tracing = { version = "0.1", features = ["log"] }
+tracing-subscriber = { version = "0.3", default-features = false, features = ["fmt"] }
+uuid =   { version = "1.4.1", features = ["v4"]}

examples/http-runtime-hooks/README.md

@@ -0,0 +1,11 @@
+# AWS Lambda Function example
+
+## Build & Deploy
+
+1. Install [cargo-lambda](https://github.com/cargo-lambda/cargo-lambda#installation)
+2. Build the function with `cargo lambda build --release`
+3. Deploy the function to AWS Lambda with `cargo lambda deploy --iam-role YOUR_ROLE`
+
+## Build for ARM 64
+
+Build the function with `cargo lambda build --release --arm64`

examples/http-runtime-hooks/src/main.rs

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+use lambda_http::{crac, service_fn, Body, Error, IntoResponse, Request, RequestExt, Response, Runtime};
+use std::sync::Arc;
+use std::sync::RwLock;
+use uuid::Uuid;
+
+struct SharedClient {
+    name: &'static str,
+    secret: Arc<RwLock<String>>,
+}
+
+impl SharedClient {
+    fn new(name: &'static str, secret: String) -> Self {
+        Self {
+            name,
+            secret: Arc::new(RwLock::new(secret)),
+        }
+    }
+
+    fn response(&self, req_id: String, first_name: &str) -> String {
+        format!("{}: Client ({}) invoked by {}.", req_id, self.name, first_name)
+    }
+}
+
+impl crac::Resource for SharedClient {
+    fn before_checkpoint(&self) -> Result<(), Error> {
+        // clear the secret before checkpointing
+        {
+            let mut write_lock = self.secret.write().unwrap();
+            *write_lock = String::new();
+        } // release the write lock
+
+        {
+            tracing::info!("in before_checkpoint: secret={:?}", self.secret.read().unwrap());
+        } // release the read lock
+
+        Ok(())
+    }
+    fn after_restore(&self) -> Result<(), Error> {
+        // regenerate the secret after restoring
+        {
+            let mut write_lock = self.secret.write().unwrap();
+            *write_lock = Uuid::new_v4().to_string();
+        } // release the write lock
+
+        {
+            tracing::info!("in after_restore: secret={:?}", self.secret.read().unwrap());
+        } // release the read lock
+
+        Ok(())
+    }
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    // required to enable CloudWatch error logging by the runtime
+    tracing_subscriber::fmt()
+        .with_max_level(tracing::Level::INFO)
+        // disable printing the name of the module in every log line.
+        .with_target(false)
+        // disabling time is handy because CloudWatch will add the ingestion time.
+        .without_time()
+        .init();
+
+    // Create the "client" and a reference to it, so that we can pass this into the handler closure below.
+    let secret = Uuid::new_v4().to_string();
+    let shared_client = SharedClient::new("random_client_name_1", secret);
+    let shared_client_ref = &shared_client;
+    {
+        tracing::info!(
+            "In main function: secret={:?}",
+            shared_client_ref.secret.read().unwrap()
+        );
+    } // release the read lock
+
+    // Define a closure here that makes use of the shared client.
+    let handler_func_closure = move |event: Request| async move {
+        {
+            tracing::info!(
+                "In handler function: secret={:?}",
+                shared_client_ref.secret.read().unwrap()
+            );
+        } // release the read lock
+
+        Result::<Response<Body>, Error>::Ok(
+            match event
+                .query_string_parameters_ref()
+                .and_then(|params| params.first("first_name"))
+            {
+                Some(first_name) => {
+                    shared_client_ref
+                        .response(
+                            event
+                                .lambda_context_ref()
+                                .map(|ctx| ctx.request_id.clone())
+                                .unwrap_or_default(),
+                            first_name,
+                        )
+                        .into_response()
+                        .await
+                }
+                None => Response::builder()
+                    .status(400)
+                    .body("Empty first name".into())
+                    .expect("failed to render response"),
+            },
+        )
+    };
+
+    // Pass the closure to the runtime here.
+    Runtime::new()
+        .register(shared_client_ref)
+        .run(service_fn(handler_func_closure))
+        .await?;
+    Ok(())
+}